Fig. 7
Examples of difficult metabolite assignments—and therefore quantitation—in urine. a TMAO and TMA are biomarkers of trimethylaminuria; however, accurate determination of TMAO concentration is challenging since many metabolite signals (δ obs) are in the same spectral region and should be properly subtracted. To do so, the position of each of them must be known accurately, and it is indeed successfully predicted (δ pred) by our predictor, leading to accurate quantitation of TMAO. b The creatine/creatinine concentration ratio is an important clinical parameter, but this ratio is difficult to determine due to the severe overlap between the creatine and creatinine signals. Again, it is shown that the δ value of creatine (although its signal is largely hidden under the strong creatinine peak) is accurately predicted. In crowded spectral areas, several unique signals of metabolites are present, making their assignment very risky. Nevertheless, our predictor always provides accurate chemical shifts predictions as shown for c guanidoacetate, d dimethyl sulfone, and e succinate, in perfect agreement with the observed values, validated by spiking experiments for each metabolite
